New cancer drugs wake up sleeping killer T cells

The frontline immune system fighters, often evaded by tumors, might now resume the attack

LOCK AND LOAD In this computational image, a ligand protein binds to precise spots (yellow) on a T cell’s receptor protein PD-1, acting like a key in a lock. This activates PD-1 to send a signal that puts the T cell to sleep, making it oblivious to cancer. Such precise modeling may help researchers create drugs that disrupt the connection — awakening T cells and making cancer “visible.”

K. BARAKAT AND M. AHMED/RECEPTORS & CLINICAL INVESTIGATION 2015

Cancer relies on a bag of tricks that can render it virtually invisible to the body’s disease-fighting apparatus. Tumors even co-opt “checkpoint” proteins found on the immune system’s T cells. These proteins normally prevent the immune system from running amok. When activated, these checkpoints can turn a T cell from a bristling warrior ready for a fight into a dozing sentinel — and cancer takes full advantage.

Now, though, new drugs that disable these checkpoint proteins are showing a keen ability to awaken T cells and, in so doing, pull away cancer’s veil. In the last year, studies testing a handful of these drugs have demonstrated eye-opening results against melanoma — the deadly kind of skin cancer — and tangible gains against other malignancies.

The results have sent a jolt through a research community that had grown doubtful about harnessing the immune system to fight cancer. “The sun is finally

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